Process for preparing dialkylbenzene lubricant composition



United States Patent Ofice 3,538,178 PROCESS FOR PREPARINGDIALKYLBENZENE LUBRICANT COMPOSITION Roy C. Sias, Ponca City, Okla.,assignor to Continental Oil Company, Ponca City, Okla., a corporation ofDelaware No Drawing. Filed Apr. 1, 1969, Ser. No. 812,373 Int. Cl. C07c3/00, 3/50; Cm 3/10 US. Cl. 260-672 10 Claims ABSTRACT OF THE DISCLOSUREA process for preparing a di-n-alkylbenzene lubricant composition havingimproved pour point and low temperature viscosity properties isdescribed. The process comprises disproportionation ofmono-n-alkylbenzenes using a Friedel-Crafts catalyst (e.g., AlCl in thepresence of n-alkyl chlorides (R=C C Preferably, themono-n-alkylbenzenes are pretreated with a Friedel-Crafts catalystbefore disproportionation. The alkyl group of the monoalkylbenzenes andeach of the alkyl groups of the dialkylbenzene contains from about 8 toabout 18 carbon atoms. In order to concurrently produce a good yield andimproved physical properties the reaction temperature is maintained inthe range of 75 to 85 C.

RELATED APPLICATIONS The following applications have the same assigneeas the present application.

Ser. No. 529,284, filed Feb. 23, 1966, discloses and claims a processfor preparing di-n-alkylbenzenes by the disproportionation ofmono-n-alkylbenzenes using a Friedel-Crafts catalyst (preferably AlClSer. No. 725,908, filed May 1, 1968, discloses a lubricant compositioncomprising a mixture of dialkylbenzenes and monoalkylbenzenes.

BACKGROUND Various petroleum fractions have been used as lubricants formany years. While the petroleum-derived lubricants have beensatisfactory for most uses, there are fields of use, as for example, jetengine lubricants and arctic oils, wherein the requirements render theconventional petroleum-derived lubricants either unsatisfactory or ofmarginal utility. In an attempt to solve this problem syntheticlubricants (for example, diesters) have been developed having improvedproperties, particularly improved "viscosity and pour point properties.Unfortunately, however, the synthetic lubricants of the prior art havebeen relatively expensive.

In an effort to provide lower-cost, high quality synthetic lubricants,work has been directed to synthetic hydrocarbons. For example, Pappasand Kant in US. 3,173,965 teach that dialkylbenzenes (R- C to C haveproperties which render them useful as lubricants. In addition, Be-'craft and Durr, in U.S. 3,288,716, teach that a bottoms fraction of theproduct resulting from the condensation of a substantiallystraight-chain parafiinic hydrocarbon, containing in the range of about8 to about 18 carbon atoms, with an aromatic hydrocarbon, has propertieswhich render it particularly useful as a lubricant.

I have discovered a process for preparing an improved di-n-alkylbenzenelubricant composition, wherein, briefly Patented Nov. 3, 1970 stated,the process comprises disproportionation of mono n-alkylbenzenes using aFriedel-Crafts catalyst (e.g., AlCl in the presence of n-alkyl chlorides(R=C -C Preferably, the mono-n-alkylbenzenes are pretreated with AlClprior to disproportionation. When it is desirable to concurrentlyproduce a good yield and improved physical properties thedisproportionation reaction temperature is maintained in the range of toC.

PRIOR ART US. Pat. No. 2,688,643, to Raymond M. Dean et al., teaches aprocess for preparing an alkyl aromatic hydrocarbon which is useful as apour point depressant. The process comprises alkylating an aromatichydrocarbon with a haloalkane (C to C using a Friedel-Crafts catalyst.The catalyst may be in the form of a complex with a short-chain alkylhalide, e.g., methyl chloride.

Numerous patents (e.g., US. 2,753,384 to Arthur P. Lien et al.) teachthe preparation of dialkylbenzenes (R=C or less) by thedisproportionation of monoalkylbenzenes using a Friedel-Crafts catalyst.In general the prior art on disproportionation teaches that the methodcannot be used on higher alkylbenzenes (R is above a C since cleavageand fragmentation of the alkyl chain occurs.

In addition to US. 2,688,643, discussed above, a search of the prior artproduced the following US. Pats: 2,852,575; 3,173,965; 3,251,898;3,281,483; 3,288,716; 3,342,886; 3,355,508; 3,392,206; 3,398,206;1,658,176; 2,495,323; 3,031,513; 3,068,302. Since the above-listedpatents are of no more pertinency than the references discussed hereinit is not considered necessary that they be discussed.

To applicants knowledge there is no prior art teaching thedisproportionation of C C mono-n-alkylbenzenes using a Friedel-Craftscatalyst in the presence of a C -C n-alkyl chloride. In addition, thereis no prior art which teaches pretreatment of the mono-n-alkylbenzeneswith a Friedel-Crafts catalyst prior to the disproportionation reaction.Furthermore, there is no prior art which teaches that a temperaturerange of 75-85" C. in the disproportionation reaction provides anoptimum balance with regard to yield and physical properties.

BRIEF SUMMARY OF THE INVENTION Broadly stated, the present inventionrelates to a process for preparing a di-n-alkylbenzene lubricantcomposition, having improved pour point and low temperature viscosityproperties, said process comprising:

(a) Forming an admixture of mono-n-alkylbenzenes and n-alkylchlorides,the alkyl groups of which contain from about 8 to about 18, preferablyfrom about 10 to about 14 carbon atoms;

(b) Contacting the admixture of step (a) with a Friedel-Crafts catalystunder reaction-promoting conditions, and

(c) Recovering from the reaction mass of step (b) a bottoms fractionconsisting essentially of di-n-alkylbenzenes.

Preferably, the mono-n-alkylbenzenes are treated with a Friedel-Craftscatalyst prior to conducting the reaction. In addition, when it isdesirable to concurrently produce a good yield and improved physicalproperties the disproportionation reaction temperature is maintained inthe range of 75 to 85 C.

In another aspect, the present invention relates to a di-n-alkylbenzenelubricant composition prepared by the above-described processes.

DETAILED DESCRIPTION Materials used Suitable mono-n-alkylbenzenes arethose containing from about 8 to about 18 carbon atoms in the alkylgroups. Preferably the alkyl groups contain from about 10 to about 14carbon atoms. The term n-alkylbenzenes as used herein refers to benzenecontaining a substantially straight chain alkyl group, wherein at least95 percent of the alkyl substituents are bonded to the benzene nucleusthrough a secondary carbon atom of the respective alkyl group.

In addition to pure mono-n-alkylbenzenes meeting the foregoingdescription my process can use mixtures of the describedmono-n-alkylbenzenes and hydrocarbon compositions containing substantialamounts of mixtures of the described mono-n-alkylbenzenes.

A particularly suitable material for use in my process is a composition,containing a substantial amount of monon-al'kylbenzeues conforming tothe foregoing description, produced in accordance with the process ofUS. Pat. No. 3,316,294. Briefly, US. 3,316,294 relates to a process ofpreparing a detergent alkylate, wherein the process comprises thefollowing steps, broadly stated:

(a) Separating a fraction of substantially straightchain C -Chydrocarbons from a petroleum distillate substantially free of olefinsand containing said straightchain hydrocarbons together withnon-straight chain hydrocarbons;

(b) Chlorinating said fraction to the extent whereby between about 10and about 35 mole percent of the straight-chain hydrocarbons present aresubstantially only mono-chlorinated;

(c) Alkylating an aromatic compound, e.g., benzene, with thechlorination product of step (b) in the presence of an allcylationcatalyst, and

(d) Recovering from the reaction mass, by distillation, a fractionconsisting essentially of mono-n-alkylbenzenes.

N-alkylbenzenes of the type described in the foregoing are availableunder the trademarks Nalkylene 500 and Nalkylene 600 from ContinentalOil Company. These materials have the following typical properties:

NALKYLENE 500 Test Typical value Test method Boiling range, F 535-595ASTM D-447. Bromine No 0.05 max ASTM D-1I58. Average molecular weig231-241 Mass spec Color, Saybolt Specific Gravity, 20/20.--. 0.85-0.87ASTM D-287. Viscosity, Saybolt seconds 40-45 at 100 F- ASTM 88-44.

NALKYLENE 600 Test Typical value Test method Bolling range, F ASTMD-477.

5% 580-590. 95% 6006l5 Bromine No 0.05 max... PM. #921. Averagemolecular weight 255-264 Mass spec. Color, Saybolt 25 min- PM. #20.Specific gravity .850.87 ASTM D-287.

0 Viscosity, Saybolt sec0nds-. 40-46 at 100 F ASTM 88-44.

Suitable n-alkyl chlorides are normal paratfins chlorinated to theextent that from about 10 and about 35 mole percent are substantiallyonly monochlorinated. Particularly suitable n-alkyl chlorides are thoseprepared in accordance with U8. 3,316,294, described hereinbefore.Preferred n-alkyl chlorides are those wherein the hydrocarbon portionhas a molecular weight in the range of 154 to 164, in other words, thealkyl groups correspond to that of Nalkylene 500', described above.

A Friedel-Crafts catalyst is used in the disproportionation reaction.The term Friedel-Crafts catalyst is believed to be well understood inthe art and refers in general to materials such as aluminum halides,boron trifluoride, boron trichloride, antimony chlorides, stannicchloride, zinc chloride and mercuric chloride. Of the Friedel-Craftscatalysts aluminum chloride is preferred. Ordinarily, when aluminumchloride is used as a disproportionation catalyst, a promoter such aswater or hydrogen chloride is employed. It is of interest that nopromoter per se is employed in the process of my invention.

PROCESS CONDITIONS Disproportionation reaction A suitable amount ofn-alkyl chlorides for the disproportionation reaction is from about 0.1to about 3 moles per mole of aluminum chloride (or other Friedel-Craftscatalyst). Preferably, on the same basis, the amount of n-alkylchlorides is from about 0.5 to about 1.5 moles.

When aluminum chloride is used as the catalyst, a suitable amount isfrom about 0.50 to about 5 percent by weight based on themono-n-alkylbenzenes (or pretreated mono-n-al'kylbenzenes). Preferably,on the same basis, the amount of aluminum chloride is from about 1 toabout 2 percent by weight.

Temperatures in the range of from about 50 C. to about C. are suitablefor conducting the disproportionation reaction. I have found that whenit is desirable to obtain a good yield concurrently with improved pourpoint and low temperature viscosity properties it is preferable to use atemperature in the range of about 75 to about 85 C. More preferably thetemperature is about 80 C. Temperatures below the preferred range resultin a decrease in yield and an increase in the -40 F. viscosity, with thepour point staying substantially the same. Temperatures above thepreferred range result in an increase in yield and a decrease in the 40F. viscosity, but result in an increase (i.e., higher) in the pourpoint.

Reaction times in the range of from about 5 minutes to about 180 minutesare suitable in the disproportionation reaction. Knowing the otherconditions of the process of my invention anyone skilled in this art,without undue experimentation, can readily determine the optimumreaction time.

Following the disproportionation reaction the reaction mass is treatedto remove unconsumed catalyst and subjected to a distillation to recoverthe desired bottoms product. Since those skilled in this art arefamiliar with the steps of treating the crude alkylate it is unnecessaryto discuss this procedure herein.

With regard to the distillation, a cut-point of about 197 C. at 5 mm. Hgis preferable in order to obtain a bottoms product having the desiredproperties.

PRETREATMENT Pretreatment of the mono-n-alkylbenzenes provides animprovement in the 40 F. viscosity of the final product(di-n-alkylbenzenes). In addition, it provides a small increase (from 2to 4 percent) of the yield of final product. In view of theseimprovements, the preferred aspect of the process of my lnventionincludes the additional step of pretreating the mono-n-alkylbenzenes.

In conducting the pretreatment, a suitable amount of aluminum chlorideis from about 0.5 to about percent by weight of themono-n-alkylbenzenes. Preferably, on the same basis, the amount ofaluminum chloride is about 1 percent.

Temperature and time do not appear to be critical in the pretreatmentstep. Temperatures in the range of from about 40 to about 80 C. andtimes in the range of from about 15 to about 60 minutes are suitable.

The Sludge which results from the pretreatment is separated from thehydrocarbons prior to conducting the disproportionation reaction.

USES FOR MY LUBRICANT COMPOSITION The lubricant composition disclosedherein can be used per se in a variety of applications. It can be usedto lubricate internal combustion and diesel engines under very lowtemperature operating conditions. In addition it can be used tolubricate turbojet aircraft engines. Still further, it is particularlyuseful in automatic transmissions.

While my lubricant composition may not meet all of the physical propertyrequirements set forth in the various arctic oil and jet enginelubricant specifications, the composition is so close to meeting therequirements that only minor blending with other lubricants is requiredto meet the specification. For example, copending application Ser. No.725,908, referred to in the foregoing discloses a lubricant compositioncomprising a mixture of dialkylbenzenes and monoalkylbenzenes. Additionof a small amount of monoalkylbenzenes enables the presentdialkylbenzene composition to meet the required specifiiation. In orderto illustrate how closely the lubricant composition of my inventioncomes to meeting the required arctic oil and jet engine lubricantspecifications, these specifications are set forth below. Mil-L-l0295Ais an arctic oil specification, while Mil-L-23699A is a jet enginelubricant specification.

MILL-10295ASPEOIFICATIONS Requirement limits Physical property MinimumMaximum Viscosity, kinematic, 05.: At 210 F At -40 F 8, 500 Four point,F 65 Stable pour point, F. 65 Flash point, COO, F 290MIL-L-23690A-SPECIFIOATIONS Requirement limits Physical property MinimumMaximum Viscosity, kinematic, cs.:

At 210 F At 100 F 25. 0

All 40 F- 13,000 Flash point, F. (000) Pour point, F -65 In order todisclose the nature of the present invention still more clearly, thefollowing illustrative examples will be given. It is to be understoodthat the invention is not to be limited to the specific conditions ordetails set forth in these examples except insofar as such limitationsare specified in the appended claims.

EXAMPLE 1 PRET-REATMENT The mono-n-alkylbenzene was added to a creasedreaction flask. While employing mechanical agitation the contents of theflask were heated to 40 C. whereupon the anhydrous AlCl (one wt.percent) was added and the reaction continued for 30 minutes at 40*45 C.The reaction product Was then [gravity settled for 2 hours at ambienttemperature. The crude alkylate phase was separated from the sludgephase by decantation and reserved for disproportionation; the sludge wasdiscarded.

DISPROPORTIONATION Materials Pretreated alkylate-600 g. Anhydrous A1Cl-6.0 g. (0.045 mole) Alkyl chlorides 4.6% Cl39.3 g. (0.055 mole) Thepretreated alkylate was added to a creased reaction flask and, whilemechanical agitation was used, heated to 65 C. The AlCl and alkylchlorides were then added to the reaction vessel and heating continuedto C. The reaction was maintained at 80 C. for one hour, after which thereaction mass Was transferred to a separatory funnel where it wasgravity settled for 1 hour at ambient temperature. The alkylate phasewas separated from the sludge phase and washed as follows: 300 ml.Water, 300 ml. 5% aqueous NaOH, then three 300 ml. to neutral point(Hydroin paper). The last gravity settle period was overnight. Thewashed alkylate was then distilled with the following fractions beingobtained:

(a) benzene (b) paraflin (c) monoakylate (d) Bottoms-di-n-alkylbenzenes(material boiling above 197 C. at 5 mm. Hg.)

The bottoms fraction was then treated with 1.25 wt. percent Filtrol clayand filtered through Hyflo.

The data on each of the runs and on a composite of the runs are shownbelow.

Run No.

A B Composite Yield 1 25. 9 27. 0 Viscosity, cs F 100. 32.85 30.99 31.80210 5. 44 5. 24 5. 36 -40 11, 044 10, 288 10, 611 V.I 112 111 113 Pourpoint, F 70 65 70 Flash, (3.0.0., F 470 Evaporation low, wt. percent(6.5 hours,

1 Grams bottoms/grams mono-n-alkylbenzeues charged/100.

EXAMPLE 2 This example uses a series of runs to illustrate the effect ofpretreatment and varying amounts of alkyl chlorides.

The mono-n-alkylbenzenes and alkyl chlorides were the same as inExample 1. The process conditions were the same as in Example 1, except.for pretreatment and amount of alkyl chlorides. Where pretreatment wasused, the conditions were the same as in Example 1.

EXAMPLE 3 DISPROPORTIONATION RUNS IN EXAMPLE 2 Run No.

A B C D E F G Yes Yes Yes N o N o No Yes 600 600 600 600 600 600 600 1.01.0 1.0 1. 5 1.5 1. 5 1.0 0.045 0. 045 0. 045 0. 067 0. 067 0.067 0. 0459. 3 19. 7 78. 6 19. 7 39. 3 78. 6 None Mols Q1 charged 0.012 026 0.100.026 0.051 0.10 None Reaction time, hon 1 l l 1 1 1 1 Reactiontemperature, 80 80 80 80 80 80 80 M C1 [M A1013 0. 27 0. 58 2. 22 0. 390. 70 1. 49 None Crude alkylate, g 5 (3. 3 542. 1 637.0 591. 0 612.3650. 4 577. 6 81511231150011 Chg. g 576. 8 532. 6 623. 2 584. 9 606. 5628. 5 563. 7

Benzene fraction/alkylate chg." 100 4. 4 3. 9 3. 5 2. 2 2. 4 3. 4 3. 5Paraflin fraction/alkylate chg. X100 8.8 7. 1 14. 0 10.0 8.6 13.0 3. 5Monoalkylate fraction/alkylate chg. X1 64. 2 56. 0 59. 0 64. 2 66. 4 69.9 65. 1 Btms. fracticn/alkylate chg. X100 23.4 22. 2 27. 8 20.3 22.7 21.7 22. 6 Bottoms properties, viscosity, cs.:

1 Alkylchlorides 4.6 wt. percent CI. 1 G.; 01, 35.46. 3 Present asalkylchlorides.

EXAMPLE 3 Run No.

A B C D E F Disproportionation conditions:

Temp., C 110 so 50 so 50 Time, hrs" 1 2 2 1 2 2 PromotiorL... HCl 1'] ClIlCl H20 H20 1120 Wt. percent AlCl; l. 0 2. 0 2. 0 l. 5 1. 5 2. 0Properties of bottoms:

Viscosity, 05., -40 F 12,297 10,000 10, 370 12,035 13, 038 13,052 V.I113 116 118 101 111 Your point, F -60 55 60 60 65 70 Yield, percent 29.232. 1 19. 7 29.1 20. 5 11. 8

While particular embodiments of the invention have 3. The process ofclaim 2 wherein said mono-n-alkylbeen described, it will be understood,of course, that the benzenes are pretreated with aluminum chloride.

(a) forming an admixture of mono-n-alkylbenzenes and n-alkylchlorides,the alkyl groups of said mono-nalkylbenzenes and said n-alkylchloridescontaining from about 8 to about 18 carbon atoms,

(b) contacting the admixture of step (a) with from about 0.5 to about 5weight percent, based on said mono-n-alkylbenzenes, of a Friedel-Craftscatalyst under reaction-promoting conditions,

(c) recovering from the reaction mass of step (b) a bottoms fractionconsisting essentially of di-n-alkylbenzenes,

said process being characterized further in that said nalkyl-chloridesof step (a) are present in an amount in the range of from about 0.1 toabout 3 moles per mole of said Friedel-Crafts catalyst in step (b).

2. The process of claim 1 wherein said Friedel-Crafts catalyst isaluminum chloride,

4. A process for preparing a di-n-alkylbenzene lubricant composition,each of the alkyl groups of said di-nalkylbenzenes containing from about10 to about 14 carbon atoms, said lubricant composition having a pourpoint of at least 65 F., said process consisting essentially of:

(a) forming an admixture of mono-n-alkylbenzenes and n-alkylchlorides,the alkyl groups of said monon-alkylbenzenes and said n-alkylchloridescontaining from about 10 to about 14 carbon atoms,

(b) contacting the admixture of step (a) with from about 0.5 to about 5weight percent A101 based on said mono-n-alkylbenzenes, at a temperatureof from about 50 C. to about C. for a time in the range of from about 5to about 180 minutes,

(c) recovering from the reaction mass of step (b) a bottoms fractionconsisting essentially of di-n-alkylbenzenes,

said process being characterized further in that said nalkylchlorides ofstep (a) are present in an amount in the range of from about 0.1 toabout 3 moles per mole of aluminum chloride catalyst in step (b).

5. The process of claim 4 wherein the monoalkylbenzenes are pretreatedwith from about 0.5 to about 1.5 weight percent AlCl at a temperature inthe range of about 40 to about 80 C. and for a time of from about 15 toabout 60 minutes.

6. The process of claim 4 wherein the amount of AlCl is from about 1 toabout 2 weight percent.

7. The process of claim 6 wherein said n-alkyl-chlorides of step (a) arepresent in an amount in the range of from about 0.5 to about 1.5 molesper mole of aluminum chloride catalyst in step (b).

8. The process of claim 7 wherein the reaction temperature is from about75 to about 85 C.

9. The process of claim 8 wherein the monoalkylbenzenes are pretreatedwith from about 0.5 to about 15 Weight percent A101 at a temperature inthe range of about 40 to about 80 C. and a time of from about 15 minutesto about 60 minutes.

10. The process of claim 9 wherein the bottoms fraction is obtained bydistilling the reaction mass using a cut-point of 197 C. at 5 mm. Hg.

10 References Cited UNITED STATES PATENTS 2,688,643 9/1954 Dean et al.260671 3,173,965 3/1965 Pappas et a1 260667 3,288,716 11/1966 Becraft etal. 25259 3,316,294 4/1967 Feighner et a1. 2 60505 3,392,206 7/1968Hurley et al 260-671 DELBERT E. GANTZ, Primary Examiner G. E.SCHMITKONS, Assistant Examiner US. Cl. X.R. 260671; 25259

